(** Cache statistics *)

type t = {
  total_size : int64;
  entry_count : int;
  expired_count : int;
  pinned_count : int;
  stale_count : int;
  temporary_count : int;
}

let empty = {
  total_size = 0L;
  entry_count = 0;
  expired_count = 0;
  pinned_count = 0;
  stale_count = 0;
  temporary_count = 0;
}

let create ~total_size ~entry_count ~expired_count ~pinned_count ~stale_count ~temporary_count =
  { total_size; entry_count; expired_count; pinned_count; stale_count; temporary_count }

let of_entries entries =
  List.fold_left (fun acc entry ->
    let open Entry in
    { total_size = Int64.add acc.total_size (size entry);
      entry_count = acc.entry_count + 1;
      expired_count = acc.expired_count + (if is_expired entry then 1 else 0);
      pinned_count = acc.pinned_count + (if is_pinned entry then 1 else 0);
      stale_count = acc.stale_count + (if is_stale entry then 1 else 0);
      temporary_count = acc.temporary_count + (if is_temporary entry then 1 else 0);
    }
  ) empty entries

let total_size t = t.total_size
let entry_count t = t.entry_count
let expired_count t = t.expired_count
let pinned_count t = t.pinned_count
let stale_count t = t.stale_count
let temporary_count t = t.temporary_count

let pp fmt t =
  Format.fprintf fmt
    "Stats{entries=%d, size=%Ld, expired=%d, pinned=%d, stale=%d, temporary=%d}"
    t.entry_count
    t.total_size
    t.expired_count
    t.pinned_count
    t.stale_count
    t.temporary_count

(* Jsont support *)

(* Helper codec for int64 *)
let int64_jsont =
  let kind = "Int64" in
  let doc = "64-bit integer as number" in
  let dec n = Int64.of_float n in
  let enc i = Int64.to_float i in
  Jsont.map ~kind ~doc ~dec ~enc Jsont.number

let jsont =
  let kind = "Stats" in
  let doc = "Cache statistics" in
  let make total_size entry_count expired_count pinned_count stale_count temporary_count =
    { total_size; entry_count; expired_count; pinned_count; stale_count; temporary_count }
  in
  Jsont.Object.map ~kind ~doc make
  |> Jsont.Object.mem "total_size" int64_jsont ~enc:total_size
  |> Jsont.Object.mem "entry_count" Jsont.int ~enc:entry_count
  |> Jsont.Object.mem "expired_count" Jsont.int ~enc:expired_count
  |> Jsont.Object.mem "pinned_count" Jsont.int ~enc:pinned_count
  |> Jsont.Object.mem "stale_count" Jsont.int ~enc:stale_count
  |> Jsont.Object.mem "temporary_count" Jsont.int ~enc:temporary_count
  |> Jsont.Object.finish